import SwiftUI
import AVFoundation

#if os(macOS)
import AppKit

// MARK: - 扫码窗口（独立 NSWindow，避免 SwiftUI sheet 布局崩溃）
class QRScannerWindowController: NSObject, AVCaptureMetadataOutputObjectsDelegate {
    var window: NSWindow?
    var session: AVCaptureSession?
    var previewLayer: AVCaptureVideoPreviewLayer?
    var hostView: QRScannerHostView?
    weak var bridge: PlayerBridge?
    
    private var lastDetected: String?
    private var lastDetectedTime: Date = .distantPast
    
    init(bridge: PlayerBridge) {
        self.bridge = bridge
        super.init()
    }
    
    func show() {
        if let win = window, win.isVisible {
            win.makeKeyAndOrderFront(nil)
            return
        }
        
        let win = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 400, height: 380),
            styleMask: [.titled, .closable],
            backing: .buffered,
            defer: false
        )
        win.title = L.scanQRCode
        win.isReleasedWhenClosed = false
        win.center()
        
        // 创建宿主视图
        let container = NSView(frame: win.contentRect(forFrameRect: win.frame).insetBy(dx: 0, dy: 0))
        container.wantsLayer = true
        container.layer?.backgroundColor = NSColor.black.cgColor
        
        let hostView = QRScannerHostView(frame: NSRect(x: 20, y: 80, width: 360, height: 240))
        container.addSubview(hostView)
        self.hostView = hostView
        
        // 提示文字
        let label = NSTextField(labelWithString: L.scanHint)
        label.font = NSFont.systemFont(ofSize: 11)
        label.textColor = .secondaryLabelColor
        label.frame = NSRect(x: 20, y: 20, width: 360, height: 40)
        label.alignment = .center
        label.lineBreakMode = .byWordWrapping
        container.addSubview(label)
        
        // 检测结果文字
        let resultLabel = NSTextField(labelWithString: "")
        resultLabel.font = NSFont.monospacedSystemFont(ofSize: 12, weight: .regular)
        resultLabel.textColor = .labelColor
        resultLabel.frame = NSRect(x: 20, y: 330, width: 360, height: 30)
        resultLabel.alignment = .center
        resultLabel.lineBreakMode = .byTruncatingMiddle
        resultLabel.tag = 100
        container.addSubview(resultLabel)
        
        win.contentView = container
        
        // 配置摄像头
        setupCapture(hostView: hostView)
        
        win.makeKeyAndOrderFront(nil)
        NSApp.activate(ignoringOtherApps: true)
        self.window = win
    }
    
    func close() {
        session?.stopRunning()
        window?.close()
    }
    
    private func setupCapture(hostView: QRScannerHostView) {
        let session = AVCaptureSession()
        self.session = session
        
        guard let device = AVCaptureDevice.default(for: .video),
              let input = try? AVCaptureDeviceInput(device: device) else {
            showError("No camera available")
            return
        }
        
        if session.canAddInput(input) {
            session.addInput(input)
        }
        
        let output = AVCaptureMetadataOutput()
        if session.canAddOutput(output) {
            session.addOutput(output)
            output.setMetadataObjectsDelegate(self, queue: .main)
            output.metadataObjectTypes = [.qr]
        }
        
        let previewLayer = AVCaptureVideoPreviewLayer(session: session)
        previewLayer.videoGravity = .resizeAspectFill
        hostView.previewLayer = previewLayer
        self.previewLayer = previewLayer
        
        // 后台启动
        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            session.startRunning()
            DispatchQueue.main.async {
                self?.previewLayer?.frame = hostView.bounds
            }
        }
    }
    
    private func showError(_ msg: String) {
        guard let resultLabel = window?.contentView?.viewWithTag(100) as? NSTextField else { return }
        resultLabel.stringValue = msg
        resultLabel.textColor = .systemRed
    }
    
    // MARK: - AVCaptureMetadataOutputObjectsDelegate
    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        guard let metadata = metadataObjects.first as? AVMetadataMachineReadableCodeObject,
              let code = metadata.stringValue else { return }
        
        // 防抖 3 秒
        let now = Date()
        if code == lastDetected, now.timeIntervalSince(lastDetectedTime) < 3 {
            return
        }
        lastDetected = code
        lastDetectedTime = now
        
        // 显示检测结果
        if let resultLabel = window?.contentView?.viewWithTag(100) as? NSTextField {
            resultLabel.stringValue = code
            resultLabel.textColor = .systemGreen
        }
        
        // 检查是否为有效 URL
        if let url = URL(string: code), (url.scheme == "http" || url.scheme == "https") {
            DispatchQueue.main.async { [weak self] in
                self?.bridge?.addURL(code)
            }
            
            // 延迟关闭
            DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) { [weak self] in
                self?.close()
            }
        }
    }
    
    deinit {
        session?.stopRunning()
    }
}

// MARK: - 宿主视图
class QRScannerHostView: NSView {
    var previewLayer: AVCaptureVideoPreviewLayer?
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        wantsLayer = true
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func layout() {
        super.layout()
        previewLayer?.frame = bounds
    }
}

#endif